Pentanediamine (i.e., 1,5-pentanediamine, 1,5-diaminopentane, cadaverine) is an important polymeric monomer. Starting from 1,5-pentanediamine, a series of polyamides, such as polyamide 56, polyamide 510, or polyester amides can be synthesized, and is widely used in textiles, electronic appliances, mechanical equipment, automobiles and other fields.
The patents related to the production and purification of 1,5-pentanediamine are cited as follows:
In CN101981202A, pentanediamine is produced directly from fermentation, where a fermentation broth is refluxed at 103° C. for 5 hours to cleave the by-products contained therein, which is then subjected to multiple extractions with butanol, and evaporation of the organic solvent to obtain a pentanediamine product. In the process of extracting pentanediamine with an organic solvent, due to the characteristics of pentanediamine, polar organic solvents are usually used for the extraction. In such a process, organic solvents such as chloroform or butanol are used. During extraction, solvent is inevitably volatilized, causing environmental pollution, and thus a subsequent solvent recovery step must be performed, which increases the extraction cost.
In CN200980121108, the enzyme solution of pentanediamine is treated with an organic membrane of UF12000 molecular weight to reduce the trifunctional organic matter in the reaction solution. The treated pentanediamine solution is heated to above 100° C. to decompose pentanediamine carbonate, followed by distillation of pentanediamine to obtain the product. Decomposition of carbonate requires a relatively high temperature and long-time heating, whereas a complete decomposition of carbonate is not guaranteed, which has an adverse affect on the distillation process and product quality. This method is only suitable for the separation of 1,5-pentanediamine from pentanediamine carbonate, and thus its suitability is very limited.
CN 101970393A discloses a process comprising a step of adding an alkaline solution and subjecting the solution to nanofiltration instead of extraction to increase the recovery rate of pentanediamine. However, nanofiltration is not suitable for the case where a large amount of solid impurities is present. When the system contains a large amount of solid impurities such as bacteria or precipitates of inorganic salts or macromolecular impurities, if nanofiltration is used, pre-filtration by microfiltration or even ultrafiltration must be carried out prior to nanofiltration. Otherwise, the nanofiltration flux is low and the membrane is easily blocked, which consumes time and energy and reduces the service life of the nanofiltration membrane. Moreover, the method is basically applicable only to the case where a soluble alkali or alkali solution is added. If the pentanediamine salt is replaced with sodium hydroxide or potassium hydroxide, a large amount of salts such as sodium sulfate, sodium chloride or potassium sulfate is present in the final solution system, and precipitation in the later distillation may affect the evaporation yield of pentanediamine.